Two pipes A and B can fill a tank in 20 minutes and 30 minutes respectively. If both pipes are opened together, how much time will they take to fill the tank?
A container contains 40 litres of milk. From this container, 4 litres of milk was taken out and replaced by water. This process was repeated further two times. How much milk is now contained in the container?
If a person travels at 40 km/h, they reach their destination 10 minutes late. If they travel at 50 km/h, they reach 5 minutes early. Find the total distance.
A cistern has two taps which fill it in 12 and 15 minutes respectively. There is also a waste pipe. When all three are opened, the cistern is filled in 20 minutes. How long will the waste pipe take to empty it?